Conventionally, a display device with an image pick-up function has been proposed that can pick up an image of an object that has come close to the display due to including photodetection elements such as photodiodes in the pixels. Such a display device with an image pick-up function is envisioned to be used as a bidirectional communication display device or a display device with a touch panel function.
With a conventional display device with an image pick-up function, the photodiodes are formed in the pixels at the same time as well-known constituent elements such as signal lines, scan lines, TFTs (Thin Film Transistors), and pixel electrodes are formed on an active matrix substrate using a semiconductor process. Such a conventional display device with an image pick-up function is disclosed in JP 2006-3857A.
Also, with such a display device with an image pick-up function, there has been the problem that an offset unique to circuits such as an amplifier in the panel is added to the output of the photodetection element before it is finally output as a photosensor signal. In view of this, a proposal for automatically correcting the offset and gain of the photosensor signal is disclosed in WO 2008/126873, for example.
With the configuration disclosed in WO 2008/126873, a black level or white level detection state is artificially created using a drive pattern that is different from that of a normal sensor drive signal, and a photosensor signal is corrected using the detected level as the true black level or white level.